Pixium Vision (France)

The impact of a titania (TiO2) support film surface on the catalytic activity of gold nanoparticles (Au NP) was investigated. Using the reactive dc-magnetron sputtering technique, TiO2 films with an amorphous, anatase, and nitrogen-doped anatase crystal structure were produced for a subsequent role as a support material for Au NP. Raman spectra of these TiO2 films revealed that both vacuum and NH3 annealing treatments promoted amorphous to anatase phase transformation through the presence of a peak in the 513–519 cm−1 spectral regime. Furthermore, annealing under NH3 flux had an associated blue shift and broadening of the Raman active mode at 1430 cm−1, characteristic of an increase in the oxygen vacancies (VO). For a 3 to 15 s sputter deposition time, the Au NP over TiO2 support films were in the 6.7–17.1 nm size range. From X-ray photoelectron spectroscope (XPS) analysis, the absence of any shift in the Au 4f core level peak implied that there was no change in the electronic properties of Au NP. On the other hand, spontaneous hydroxyl (–OH) group adsorption to anatase TiO2 support was instantly detected, the magnitude of which was found to be enhanced upon increasing the Au NP loading. Nitrogen-doped anatase TiO2 supporting Au NP with ~21.8 nm exhibited a greater extent of molecular oxygen adsorption. The adsorption of both –OH and O2 species is believed to take place at the perimeter sites of the Au NP interfacing with the TiO2 film. XPS analyses and discussions about the tentative roles of O2 and –OH adsorbent species toward Au/TiO2 systems corroborate very well with interpretations of density functional theory simulations.

Introduction When fundus examination is not possible, ultrasonography (US) is an accurate tool for the diagnosis of retinal tears (RT). The aim of this study was to describe the predominant location of RT, the factors influencing their location, and the vitreous status of eyes with RT using US. Methods A prospective study was conducted in all patients diagnosed with RT by B-scan US (Aviso, Quantel Médical, Clermont-Ferrand, France). The primary endpoint was to assess RT preferential location using US. Secondary endpoints were the rate of posterior vitreous detachment (PVD), number of eyes with multiple RT, and axial length (AL). Results A total of 101 eyes of 100 patients with RT were included. RT main location was in the superior quadrants (either nasal superior, strictly superior, or temporal superior) in 71% of cases. All patients were diagnosed with PVD by US, and 79% had a vitreous hemorrhage. Twelve eyes (13%) were diagnosed with multiple RT. The mean AL was 24.62 ± 2 mm, and it was significantly longer in eyes without superior RT (25.52 mm versus 24.37 mm; p=0.004). Conclusion In this study, we showed a superior location of RT diagnosed by US in more than two-thirds of cases associated with a significantly shorter AL than in other locations. This finding could increase US sensitivity for RT detection and help to improve the US learning curve of ophthalmologists in training and surgical decision-making when the retina is inaccessible due to opacity media.

To describe unusual retinal findings of a patient affected by hemochromatosis. Case report of a 49-year-old patient who presented a progressive loss of vision. Fundus photography, fluorescein angiography, full-field electroretinogram, autofluorescence imaging, and spectral domain optical coherence tomography were performed. The patient was known to be homozygous for the C282Y mutation in the HFE gene. Visual acuity was measured at 20/20 on his right eye and 20/25 on his left eye. Retinal imaging showed alterations of the retinal pigment epithelium clearly visible on fundus autofluorescence and fluorescein angiography. The spectral domain optical coherence tomography showed retinal pigmentary epithelial atrophy associated with irregularities and focal interruption of the ellipsoid zone. A thin retina was also observed in the foveolar region associated to a thickened choroid. Full-field electroretinogram showed a decrease of rods and cones responses. Here, the authors describe the retinal findings of a patient affected by hemochromatosis, characterized by unusual retinal pigment epithelium changes associated to altered visual function. The authors hypothesize that the retinopathy could be linked to hemochromatosis because of the pathophysiology of iron homeostasis and the toxicity of iron overload for the photoreceptors.

ABSTRACT Thermo-elastic distortions of composite structures have been measured by a holographic camera using a BSO photorefractive crystal as the recording medium. The first test campaign (Phase 1) was performed on CFRP struts with titanium end-fittings glued to the tips of the strut. The samples were placed in a vacuum chamber. The holographic camera was located outside the chamber and configured with two illuminations to measure the relative out-of-plane and in-plane (in one direction) displacements . The second test campaign (Phase 2) wa s performed on a structure composed of a large Silicon Carbide base plate supported by 3 GFRP struts with glued Titanium end-fittings. Thermo-elastic distortions have been measured with the same holographic came ra used in phase 1, but four illuminations, instead of two, have been used to provide the three components of displa cement. This technique was specially developed and validated during the phase 2 in CSL laboratory. The system has been designed to measure an object size of typically 250x250 mm²; the measurement range is such that the sum of the largest relative displacements in the three measurement directions is maximum 20 µm. The validation of the four-illuminations technique led to measurement uncertainties of 120 nm for the relative in-plane and out- of-plane displacements, 230 nm for the ab solute in-plane displacement and 400 nm for the absolute out-of-plane displacement. For both campaigns, the test results have been compared to the predictions obtained by finite element analyses and the correlation of these results was good. Keywords: Holographic interferometry, Photorefractive crystal, Composite structure, 3D, Thermo-elastic distortion, Finite element model,

[Departement_IRSTEA]Territoires [TR1_IRSTEA]SYNERGIE

A new passive technique approach to phase lock a laser array is proposed and analyzed. It improves the laser combining efficiency with a large number of emitters. Our architecture combines selective coupling based on phase-contrast filter and resonant phase nonlinearity of amplifiers. A numerical study predicts that with 20 fiber lasers the architecture leads to a phase locking efficiency which is twice the value observed up to now in published experiments.

Placed on the Sun-Earth L2 Lagrange point, SPICA will operate in the 5 to 210 μm wavelength range. Astrium has been contracted by ESA/ JAXA to update the study of the SPICA telescope from a 3.5 m design (compatible to the Japanese HIIB launcher) to a 3.2 m design (compatible to the HII-A with the short 5S fairing): despite a similar fairing diameter, the shorter length of the fairing envelope results in a reduction of the M1-M2 distance and an associated diameter reduction of M1. Maximization of the M1-M2 distance within the constraints is important to maintain a reasonable polishing criteria of the main reflector. Therefore the M2 assembly sizing and the back focal length become main parameters for the telescope optical design. The main constraints are driven by the telescope requirements such as focal length, maximizing the diameter of M1 (3.2 m) and, M1 f-number (critical for the manufacturing aspects). The WFE must be below 350 nm rms, and operational temperature below 6K. . The main issues addressed in this paper are: - an improved telescope design based on the Astrium background in Silicon Carbide technology which has been tried-an-tested for mirrors and structural parts on several space projects, including HERSCHEL and Gaia (brazing, polishing, assembling, iso-static mountings). - performances which are taking advantage of the SiC properties ,such as homogeneity of the single-phase material inside the structure, and structural stability from ambient to the operational temperature range. Our study shows that the SiC telescope design can fulfil all the mechanical and optical requirements for SPICA. - the verification and optical tests definition which will be key elements in the qualification of the telescope to be incorporated in the logic of the satellite verification activity to be conducted in Japan.

This paper presents research funded by European Space Agency (ESA) / European Space Research and Technology Engineering Centre (ESTEC) into the development of technology to incorporate security functions into spacecraft flight software. The security functions are derived from the time and space partitioning mechanism within the Integrated Modular Avionics (IMA) concept. ESA is establishing a software reference architecture for future avionics that consists of a layered architecture with defined interfaces and functionality, and abstraction levels per layer. The lower level layers handle the computer issues and each progressively higher layer adds increasing functionality and services up to the implementation of the flight software applications. This approach is complementary to the Multiple Independent Levels of Security (MILS) concept. The security components are added at the lowest layer in the form of a separation kernel which is responsible for enforcing the time and space partitioning of the flight software. The security components complement the safely critical elements of a separation kernel with measures to enforce the confidentiality, integrity and availability of data. The research study used the EBIOS method to establish a set of security objectives and functional requirements for flight software. Two separation kernels were selected, one commercial and the other open-source, and successfully ported to the LEON3 spacecraft processor. An attempt was then made to verify the kernels against the security functional requirements. The verification was incomplete because the kernels did not support all of the security mechanisms specified in the requirements. However the technology has been established and can be upgraded to fully provide the security functions for future flight software.